Extraction of sulfuric acid sludge



Patented Nov. 21, 1950 EXTRACTION F SULFURIC ACID SLUDGE David W. Bransky, Chicago, 111., and Norman E.

Lemmon, Hammond, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application December 4, 1945, Serial No. 632,812

Claims.

This invention relates to improvements in the recovery of petroleum sulfonic acids from acid sludge, and more particularly to the recovery of preferentially oil-soluble sulfonic acids and water-soluble sulfonic acids from unhydrolyzed sulfuric acid sludges.

In the refining of petroleum oils with sulfuric acid, such as concentrated or fuming sulfuric acid, mixtures of sulfonic acids are produced. These sulfonic acids vary over a wide range in the degree of water-solubility and of oil-solubility. Some of these sulfonic acids, which are reddish-brown in color and which are generally referred to as mahogany acids, are preferentially oil-soluble. Another class of these sulfonic acids found in the sludge layer, which because of their greenish color are commonly referred to as green acids are preferentially water-soluble. These 50- called green acids are in fact mixtures of very water-soluble sulfonic acids which are known in the art as black acids, intermediate water-soluble detergent type sulfonic acids and preferentially oil-soluble sulfonic acids, known in the art as brown acids. The so-called black acids are more water-soluble than the intermediate water-soluble detergent type sulfonic acids, while the socalled brown acids, although preferentially oilsoluble, are less oil-soluble than are the mahogany acids.

In the usual refining process, the petroleum oil is treated with strong sulfuric acid, generally fuming sulfuric acid, and the acid sludge which is formed is separated from the acid treated oil. From the acid treated oil there are recovered the preferentially oil-soluble sulfonic acids or the so-called mahogany acids. In the acid sludge there are found the black acids, the intermediate water-soluble detergent type sulfonic acids, and the so-called preferentially oil soluble brown sulfonic acids. Heretofore, the preferentially watersoluble sulfonic acids were recovered from the acid sludge as so-called green acids, by extraction with water, water-soluble solvents, or with mixtunes of certain organic solvents and water. The extract so recovered from the acid sludge contained substantial amounts of black acids which materially decrease the detergency value of the intermediate water-soluble detergent type sulfonic acids. Also, since no attempt was made to selectively extract the sulfonic acids, the preferentially oil-soluble brown acids were lost in the so-calied green acids.

It is an object of the present invention to provide a method of recoveringpreferentially oilsoluble sulfonic acids and intermediate watersoluble detergent type sulfonic acids from unhydrolyzed sulfuric acid sludges, resulting from the treatment of hydrocarbon oils with concentrated or fuming sulfuric acid. Another object of the invention is to provide a method of selectively extracting intermediate water-soluble detergent typesulfonic-acids and preferentially oil-soluble sulfonic acids from sulfuric acid sludges resulting from the treatment of viscous petroleum oils with concentrated or fuming sulfuric acid.

We have discovered that the intermediate preferentially water-soluble detergent type sulfonic acids and the preferentially oil-soluble sulfonic acids found in sulfuric acid sludges can be selectively recovered from said sludges by extracting the same with a chlorinated aliphatic or aromatic hydrocarbon solvent, preferably the former. Examples of suitable chlorinated hydrocarbons for this purpose are carbon tetrachloride, chloroform, amyl chloride, amylene chloride, dichloroethylene, dichloromethane, dichloropentanes, ethyl chloride, methyl chloride, propylene dichloride, chloronaphthalenes, chlorinated alkylnaphthalenes, chlorobenzene, chlorinated alkylbenzenes and the like. While each of the named chlorinated hydrocarbons is effective for the herein-described purpose, it is not to be implied that all of them are equally effective. While we prefer to use chlorinated aliphatic hydrocarbons, some of the named chlorinated aliphatic hydrocarbons will be found to be more effective than others; we have found carbon tetrachloride and chloroform to be very well suited for this purpose. The ratio of chlorinated hydrocarbon solvent to the volume of unhydrolyzed sludge tobe extracted can vary from about 0.521 to 5:1; although, we prefer to use ratios of from 1:1 to 3.5:1. Temperatures employed in extracting the intermediate water-soluble detergent type sul fonic acids and the preferentially oil-soluble sulfonic acids from the unhydrolyzed acid sludge can vary from about 50 F. to about 150 F., and preferably from about F. to about F. For the most efficient extraction, it is highely desirable to provide means for intermittently contacting the unhydrolyzed acid sludge with the solvent. Suitable contact can be obtained by means of high speed propeller type stirrers or by orifice mixers; either type giving the desired degree of stirring and maximum action.

In accordance with the present invention, an unhydrolyzed sulfuric acid sludge resulting from the treatment with fuming sulfuric acid or concentrated sulfuric acid of a viscous hydrocarbon oil, that is, a hydrocarbon oil having a Saybolt a 3 Universal viscosity at 100 F. above about 45 seconds, is thoroughly mixed in the proper predetermined ratio with the chlorinated hydrocarbon solvent. After suitable contacting, the mixture and suitable as wetting and detergent agents. As another alternative, the unhydrolyzed sulfuric acid sludge can be extracted with a mixture of chlorinated hydrocarbon solvent and a of sludge and solvent is settled to permit strati- 5 hydrocarbon solvent of the herein described type ficatlon of the sludge and solvent layers and the y to extract sulfonic acids of varying water-soluchlorinated hydrocarbon solvent layer separated bility depending p the reliitive quantities of from the acid sludge layer. The former contains the two compo USed- 0 p a the intermediate water-soluble detergent type ture a ns a re r rati of the chlorinated sulfonic acids and any preferentially oil-soluble aliphatic ydrocarbon will extract sulfonic acids sulfonic acids which may have been present in Which Will rm sulfonates iv n m pr the unhydrolyzed sulfuric acid sludge, while the neuneed wetting d detergent pr p rti s. latter contains the preferentially water-soluble he recovery of intermediate water-soluble black acids and unreacted sulfuric acid. The sulfonic acids by extraction with a chlorinated sulfonic acids extracted from the acid sludge aliphatic ydro a is i u d y the da with the chlorinated hydrocarbon solvent can be tabulated in e following tab e. These data converted to the sulfonate by neutralization and were obtained by treating a y o on o l freed of the solvent to obtain a mixture of sulhaving a Saybolt Universal viscosity at 100 F. fonates. of 75-80 seconds with two pounds of turning While water-soluble detergent type sulfonic acid, drawing oil the acid sludge, then re acids of the herein described type are recoverwith one-half pound of fuming acid and drawable by the present invention from petroleum oils ing off the acid sludge which then was extracted having Saybolt Universal viscosities at 100 F. with carbon tetrachloride and with chloroform. above about 45 seconds Saybolt, the better yields For comparison, data are presented on the exare obtained from oils having Saybolt viscosities traction of the same unhydrolyzed acid sludge at 100 F. between about 70 seconds and about with a petroleum naphtha and with a blend of 350 e nds, petroleum naphtha and carbon tetrachloride.

Table Percent Yield Extracted Bullonic Acid B on Sludge Volume Solvent gagg fg latzgmcsdilate to Sludge Total Oil-Soluble ble ggg g gg Sulionate Sullonate Type lonate Naphtha 2:1 12.6 12. 6 o 80% Naphtha, 20% Carbon tetrachloride 2:1 18. 8 Carbon tetrachloride. 2:1 47 27 20 Chloroform 2:1 81 32 49 When desired the intermediate water-soluble The above data demonstrate that extracting the detergent type sulfonic acids can be selectively acid sludge with a petroleum naphtha yielded separated from the preferentially oil-soluble sulonly 12.6% of an oil-soluble sulfonic acid, while ionic acids by neutralizing the chlorinated sola blend of 80% of the petroleum naphtha and vent extract, removing the solvent from the neu- 20% of carbon tetrachloride resulted in a sultralized product, if desired, and subsequently fonate yield of 18.8%. When the acid sludge extracting sulfonates with a hydrocarbon oil, was extracted with carbon tetrachloride, a 47% preferably a distillate having a maximum AS'IM yield of total sulfonates was obtained. When distillation temperature of not more than about these sulfonates were further extracted with a 500 F., and preferably having a distillation mineral oil having a Saybolt Universal viscosity range of from about 150 F. to about 350 F. and of about 180 seconds at 100 F., a fraction repcontaining not more than about 5% aromatic resenting 27% of oil-soluble sulfonates and a hydrocarbons. Suitable hydrocarbon solvents fraction representing 20% of intermediate are light petroleum oils and petroleum naphthas, water-soluble sulfonates were obtained. When particularly virgin naphthas, of the desired disthe acid sludge was extracted with chloroform, tillation characteristics. The hydrocarbon solan 81% yield of the total sulfonates was obvents selectively extract the preferentially oil tained. When the chloroform extract was fursoluble sulfonates from the intermediate waterh r extracted with the mineral oil, a fraction soluble sulfonates. As an alternative method, epresenting 32% of oil-soluble sulfonates and the unhydrolyzed sulfuric acid sludge can first a fraction representing 49% of intermediate be extracted with a hydrocarbon solvent of the water-soluble sulfonate were obtained. The above described type to remove the preferen- 05 above data demonstrate that the herein de tially oil-soluble sulfonic acids and the acid scribed invention provides an effective means of sludge then extracted with a chlorinated hydrorecovering from sulfuric acid sludges preferencarbon solvent, preferably a. chlorinated alitially oil-soluble sulfonic acids and intermediate phatic hydrocarbon solvent, to remove the interwater-soluble detergent p sulfonic ac d w h mediate water-soluble detergent type sulfonic 7 the exclusion of the undesirable preferentially acid from the acid sludge. Each of the extracts water-soluble black acids. Alternately, a hydrocan then be neutralized and freed of the respeccarbon solvent can be added to the solution of tive solvents to produce sulfonates which are extracted sulfonic acids in chlorinated hydropreferentially oil-soluble in one case, and in carbon, thereby precipitating water-soluble dethe other sulfonates which are soluble in water 7 tergent type sulfonic acids. The water-soluble sulfonic acids with a chlorinated hydrocarbon solvent in accordance with the present invention, it is essential that the extraction be carried out in the absence of any substantial amount, that is, not more than about 1%, of added water, in order to avoid the extraction of undesirable black acids.

The term intermediate water-soluble detergent type sulfonic acids" as used herein and in the appended claims includes those sulfonic acids recovered from unhydrolyzed sulfuric a cid sludges which are water-soluble to the exclusion of any substantial quantities of preferentially water-soluble black acids. The term intermediate water-soluble sulfonates means the salt of such sulfonic acids.

The term Strong sulfuric acid as used herein and in the appended claims includes concentrated sulfuric acid of at least about 95% strength, and fuming sulfuric acids.

While we have described our invention by way of preferred embodiments, other modifications may be made without departing from the scope and spirit of this invention. We, therefore, include within the scope of our invention such modifications as come within the spirit of the appended claims.

We claim:

1. The method of recovering intermediate water-soluble sulfonic acids from unhydrolyzed sulfuric acid sludge containing water-soluble black sulfonic acids, intermediate water-soluble detergent-type sulfonic acids and preferentially oilsoluble sulfonic acids, resulting from the treat-- ment of hydrocarbon oils with strong sulfuric acid, comp-rising extracting said acid sludge with a chlorinated hydrocarbon solvent, in the absence of added water, separating the chlorinated hydrocarbon extract containing intermediate water-soluble detergent-type sulfonic acids and preferentially oil-soluble sulfonic acids, from the acid sludge, and extracting preferentially oilsoluble sulfonic acids from the chlorinated hydrocarbon extract with a predominantly aliphatic hydrocarbon solvent.

2. The method of claim 1 in which the chlorinated hydrocarbon solvent is a chlorinated aromatic hydrocarbon.

3. The method of claim 1 in which the chlorinated hydrocarbon solvent extract is neutralized prior to being extracted with the predominantly aliphatic hydrocarbon solvent.

5 4. The method of recovering intermediate water-soluble detergent-type sulfonic acids from unhydrolyzed sulfuric acid sludge containing water-soluble black sulfonio acids, intermediate water-soluble detergent-type sulfonic acids and preferentially oil-soluble sulfonic acids resulting from the treatment of hydrocarbon oils with strong sulfuric acid comprising extracting said unhydrolyzed sulfuric acid sludge with a chlorinated aliphatic hydrocarbon in the absence of added water, separating the chlorinated ali phatic hydrocarbon extract containing the inter mediate water-soluble detergent-type sulfonic acids and preferentially oil-soluble sulfonic acids from the acid sludge and extracting preferentially in oil-soluble sulfonic acids from the chlorinated aliphatic hydrocarbon extract with a predominantly aliphatic hydrocarbon solvent.

5. The method of claim 4 in which the hydrocarbon solvent is a petroleum naphtha having a maximum boiling point of less than about 500 F.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,087,888 Petroif Feb. 17, 1914 1,319,027 Divine Oct. 14, 1919 1,409,590 Salatha Mar. 14, 1922 1,474,933 Humphreys Nov. 20, 1923 2,223,194 Thompson Nov. 26, 1940 2,263,041 Lazar et al Nov. 18, 1941 2,320,738 Jenkins June 1, 1943 2,328,931 Steik Sept. 7, 1943 2,368,452 Dawson Jan. 30, 1945 FOREIGN PATENTS Number Country Date 271,433 Germany Mar. 11, 1914 85,326 Austria Jan. 15, 1921 773,656 France Nov. 23, 1934 

1. THE METHOD OF RECOVERING INTERMEDIATE WATER-SOLUBLE SULFONIC ACIDS FROM UNHYDROLYZED SULFURIC ACID SLUDGE CONTAINING WATER-SOLUBLE BLACK SULFONIC ACIDS, INTERMEDIATE WATER-SOLUBLE DETERGENT-TYPE SULFONIC ACIDS AND PREFERENTIALLY OILSOLUBLE SULFONIC ACIDS, RESULTING FROM THE TREATMENT OF HYDROCARBON OILS WITH STRONG SULFURIC ACID, COMPRISING EXTRACTING SAID ACID SLUDGE WITH A CHLORINATED HYDROCARBON SOLVENT, IN THE ABSENCE OF ADDED WATER, SEPARATING THE CHLORINATED HYDROCARBON EXTRACT CONTAINING INTERMEDIATE WATER-SOLUBLE DETERGENT-TYPE SULFONIC ACIDS AND PREFERENTIALLY OIL-SOLUBLE SULFONIC ACIDS, FROM THE ACID SLUDGE, AND EXTRACTING PREFERENTILLY OILSOLUBLE SULFONIC ACIDS FROM THE CHLORINATED HYDROCARBON EXTRACT WITH A PREDOMINANTLY ALIPHATIC HYDROCARBON SOLVENT. 